Urbanization alters species temporal activity and predator-prey overlap

Austin M. Green, Biological Sciences, University of Utah, Salt Lake City, UT, Mary E. Pendergast, Wild Utah Project, Salt Lake City, UT, Kelsey A. Barnick, Jane Addams College of Social Work, University of Illinois - Chicago, Chicago, IL and Cagan H. Sekercioglu, Biological Sciences, The University of Utah, Salt Lake City, UT; Koc University, Istanbul, Turkey

Background/Question/Methods
As the Earth’s population continues to grow, more people are moving into cities. This influx is leading to subsequent increases in built environments and urbanization, which is altering ecosystems and wildlife communities across the globe. Species are either having to adapt to their rapidly changing surroundings by altering their current niche space or retreat to remaining undeveloped lands. One way species may adapt to increases in human influence is by adopting new patterns of diel activity, which allows species to coexist in space without directly interacting with humans or one-another. However, most species’ have an innate rhythmicity to their diel activity which has evolved over the species’ full life history, and changes in these patterns may lead to deleterious consequences, like increased overlap with predators and competitors. Few studies have been able to directly compare how entire wildlife communities alter their temporal activity in response to urbanization, given the inherent difficulty in simultaneously monitoring multiple species in both metropolitan areas and undeveloped areas. In this study, we leveraged the power of 350 remote sensing camera traps and 200 community scientists to assess how urbanization has altered the temporal activity of mammals in northern Utah. Using data from both the urban Salt Lake Valley and the far-less-developed Uintah-Wasatch-Cache National Forest, we compared the diel activity pattern shifts, human temporal overlap, and coyote temporal overlap of multiple species found across both areas.
Results/Conclusions
As a whole, the community shared between the two study areas altered their temporal activity in response to urbanization. Specifically, the community in SLC became more active during the late-night hours and midday hours, with subsequent drops in crepuscular activity. On a species-specific basis, animals altered their human temporal overlap in urban areas in multiple ways: 1) no change, seen in raccoon and skunk; 2) increased overlap with humans, seen in deer, and 3) decreased overlap with humans, seen in squirrel and coyote. Predator-prey temporal overlap significantly decreased for mule deer and rock squirrel within SLC. However, sympatric carnivore temporal overlap did not change across areas. Finally, we found evidence that the shifts in activity for mule deer and rock squirrel may be affected by the use of humans as a shield against predation by coyotes. This research shows how species may adapt to human influence by altering their diel activity, and how this may be another strategy species use to avoid predation in urban environments.